The present invention relates to the manufacture of dental prostheses and more particularly to joined prostheses.
It is known that that prostheses have a metallic substructure which is fixed to the maxillary arch and ceramic crowns covered with a cermaic material or synthetic resins made by casting in a mould, followed by, if applicable, an appropriate heat treatment. The conventional procedure consisting of using a substructure made from precious alloys ensures an adequate connection between the coating and the substructure, the molten coating diffusing into the crystalline structure of the precious metal.
However, for several years now nickel-based alloys containing, for example, chromium, molybdenum or cobalt have been used for making a less complicated substructure. Prostheses made in this way have interesting qualities and a high corrosion resistance. However, the connection between the coating and the substructure is very inadequate and unreliable, the coating only adhering as a result of fritting. The coating material sometimes has a tendency to crack, break or separate from its support, despite the palliatives used (creation of a mechanical retention effect for example by hollowing out).